Spark-plug.



' A.1. MUMMERT.

SPARK PLUG.

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50 avoided. A further object of'v my invention FACTUBING COMPANY, ST. LOUIS,

imanes.

" To all whom it may concern Be it known that I, -ARDEN J. Menem, "a citizen of the United States,- residlng at My lnvention has relation to .improve,

ments in spark-plugs; and it consists -in the novel features of construction: more fully` set forth in the specificationv andpointed out in the claim.

The present improvement "is .directed to the constructionv of sparkplu sive engines, and has for its o )ect the 'con'- struction of a lug in which the 'element of member shall be minimized, thereby-.avoiding the breaking Aorcracking of said member whilein service.-y

expansion of t einsulating Aswell understood in-'ther -art theV insulating member is vgenerally constructed of porcef -lainor equivalentmaterial which is liable to` crack from overheating y reason of v its contact with the hot gases inthe engine cylm f 'electric .termina-1 3', 4the, outer end of which.-

'screwfthreadejd toreceive the screw-cap 1 der. In the 'present' embodimentA of" my. vention the size of the insulatmg membe material accumulations of ms ofv unconsumed carbon (resulting from lthe in coniplete combustion of the oil) on the lnner terminal of the insulating member, these films, as well understood 1n the art, being` lconductors of electricity and thus tending to short-circuit the sparking terminals of the plug. In'manycases however the quantity of oil reaching the region of the lug is so lare that the accumulations of t e carbon s` referred to can not be altogether therefore is to .construct a sparkfplug in which these unavoidable carbon film accuisa Figure 1 represents'a'n elevation lof my for explo- "being hereinA shown. Yconventionallyv, as grounded throughy the engine `'cylinderv f lhefinsulating" member of l soproportioned to the heat absorbed vtliereb as to maintain the vtemperature .of the' mem ber A'below the? point'fat -which vundue"expa r` 1" 'y sion and yconse nent cracking- Jthereofv 1s likely to occur. e,insulating-meanberfbef--V in thus maintained comparatlvely cool,"v itfo ows that the temperature in the c lin'de'r-v 'f in the vicinity of the plugI will be be ow the vpoint at which lubricating o1l vtindinA its way past the piston tothe region of the` plug, can. take fire, thereby reventlng any leaving an annular space .MISSOURL A CORPORATION 0F MISSOU PLUG.

practically impossible'. A vfurther object isf' to reduce the quantity of these accumula-ll f tions to a minimum so as to minimize the danger of short-circuiting, or eliminating it.: f altogether. :The advantages of the inve'u- BQ@ v tion will be apparent 'from the following detailed `description thereof in cormectiony -With the accompanying drawing in Which--A limproved spark-plug; Fig. 2 is ra middle -65 longitudinal section of the same; Fig. 3 is .sa cross-section on thejline 3-'3 of Fig. 2; and Fig. i is an elevation of the same on a Y reduced scale shovvnin position on the head of an engine cylind er.` l. v f l '70 Referringtothe 'drawings fw,"w reprev sent* the 'Wlre -terminals flea ingl from any.. available'jsoiirce of electric energy,'the iyire u: beingheld position on by fthe-1 serein-Cap .1; the, Opposite. Wire Lwf,

beln'g traversed axially yby the electrode, or1 f r which vthe wire fw, is anchored',the` wire.'A ,y

beingv clamped] between the ,screw-cap and screwed to the engine'cylinder C as .Wellfunvi' A 'derstood in the art, the socket being formed with an innerannular shoulder s for the support of 'a gasket 8 against whichthe pluV is'shouldered. The plug 2 is likewise formed .v with an `annular ledge or shoulder y. s for. the support of a gasket 9 against which is 95. firmly driven the inner end of a clamping rin' l'screwed to the inside of the socket as ully shown in Fig. 2.-`

The plus' 2.,projects int'cthe socket 7 'a considerable distance beyond' the shoulder a, said inwardly .projecting ortion being 'hereinafter referred yto as ,t e petticoatf and identified by the `reference numeral 2. The outer walls of the etticoatare spaced from the inner walls'o thev socket thereby 105 orclearance o between them (Fig. 2)..5v The 4'petticoat is formed with a bottom dome shapedl de ress'ion, ocket, or chamber substantially semi-circular in longitudinal section, com- .110

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a@ sprak-plug y.

the' nutsmestingen the washers '6,1- t. yfr-ne munication between the chamber and the annular space a being through the annular basin b formed in the socket 7 immediately beyond the shoulder m engaging the walls of the cylinder C. The inner bounding walls of the basin b adjacent end of the petticoat 2 when the plug and socket are properly assembled (the word plug wherever used without the qualifying word spark meaning always the insulating member 2, and spark-plug meaning the device as a whole). ln other words the edge e of the inner bounding wall of the basin b is disposed within the pocket or chamber h of the petticoat and in a transverse plane beyond nal (or free edge) of the petticoat, thereby forming a passageway d (between the petticoat and inner wall ot the basin 'b through which any gases must iirst dipz ownward (or toward the bottom of the basin b) before they iind their way into the clearance a.

The edge c forms the inner )terminal of the axial opening or passage-way O formed in the thread section or coupling nipple n of the socket 7, through which opening the inner portion of the electrode 3 passes and beyond which it projects to a point in proximity to the cooperating electrode 3 carried by the part n. The walls of the passage-way O are transversely ribbed or corrugated, in the present embodiment of my invention assuming the forro' of annular ledges, ribs, or ridges r Adispersed preferably at right angles to the axisfof the passageway, and in the path of the gases traversing the passage-way, said ridges being connected by sloping walls t. Any other system of roughening or 4corrugating the walls of the passage-way O would however fall within the lspirit of my invention. The cross-section of the passage-way O is suilicient to prevent accidental sparking between the electrode 3 and the walls of said passage-way. The apex ofthe dome about the chamber t is provided with a socket u for receiving the collar or enlargement 1l formed on the electrode 3, the bottom of the socket being cone-shaped as shown (Fig. 2). Obviously, the collar l1 is drawn into irm engagement with the. socket .bottom when the screw-cap l is driven home in clamping the wire w to the plug. Features shown but not alluded to are well understood in the art and require no description in the present connection.

v Should any oil or lubricant during the operation of the engine find its way past the piston to the region of the spark-plug, then necessarily withv each explosion more or less of the oil would be forced through the passage-way 0 and projected against the Y walls of the domed chamber h of the pettithe oil coat 2. A considerable portion of would forced through the passage-way project to a point beyond thev the inner termi- 4 j since even though the current either directly from the harassebe arrested by against which it would naturally impinge, so that a much smaller quantity would reach the chamber lz, than would be the case were the bore of the passage-way smooth. Should the oil arrested by the roughened walls Aof the passage-way O accumulate thereon to any material degree, it can do no harm, for notwithstanding the fact that such oilV (whether carbonized or not) is a good electric conductor, the cross-section of the opening 0 is such that the space between the oil layer and the electrode 3 will always be too reat to permit sparking between them. et us assume that a certain quantity of oil has been projected against the domed chamber h of the petticoat and that by the heat of combustion of the exploding and burning gases the oil is carbonized leaving a permanent deposit of carbono on the dome of the petticoaty chamber asy shown in Fig. 2.- Such a deposit can do no harm it should take up the current from the electrode 3 it can not communicate it to the socket 7 so as to shortcircuit the spark terminals 3, 3. The oil in being projected-or sprayed against the domed chamber h will in flected, these reflected portions being in the main projected downward (assuming the engine to be standing vertically) through the passage d into the basin b where, to some extent, the oil will lodge and orm a layer of carbon c which lis rendered harmless because too far removed from the layer 0 to short-circuit the terminals 3, 3. Finally, let us assume that some of the oil spray reaches the space a and is deposited as a layer c on the outer walls of the petticoat 2, and that the layers c and c are practically continuous so as to form a virtual extension of the electric conductor 3 with which the layer c is inevitably in electric connection. Under those circumstances the resistance which the current would encounter in traversing .the carbon layers c, c, would be in excess of the atmospheric resistance of the air gap between the sparkingtermlnals 3, 3', so that short-circuiting of these terminals would be highly improbable. Of course the carbon accumulation on the outer walls of the petticoat represents an extreme case and would result only in instances o excessive leakage of oil past the iston into the region of the spark-plu ut even should such an accumulation (c take place, the ga between it and the inner walls of `the soc et (across the space a) would be practically no less than the gap between the sparking terminals (3, 3') and when we consider the increased reslstance o'ered to the flow of the current through the carbon layers c, c, the short circuiting of the members 3, 3.', due to the passage of layer the corrugations or ribs r,

a measure be relll@ c to the metallic socket 7 (where the layer c touches the socket wall) or by a jump across the clearance a (where the layer c is not in contact with the socket wall) is highly improbable. The spark-plug as constructed therefore insures a permanent sparking between the terminals of the electrodes 3, 3', within the chamber of the engine cylinder, even under circumstances where engine trouble (due to oil finding its way past the piston into the region of the spark-plug) can not be avoided. The arrows in Fig. 2 represent the approximate pathsl taken by the projected particles of oil. The area of the walls of the cup-shaped or (lished cavity or chamber t should be sufficient to accommodate if possible most of the accumulations that are likely to result under normal working conditions, any excesses being taken care of by the basin b and the outer wall of the petticoat 2. Ob-

viously, the longitudinal section of the chamber or pocket h (or by whatever name we choose to call it) need not be as shown, but may be any suitable depression whose surface may serve as a depositing place for the spray of oil projected through the open-` ing O. The details here shown may be departed from without in any wise affecting the nature or spirit of my invention. In

all instances however, the mass of'the plug Q'should be sutlicient to absorb the heat to which the same is subjected, and subsequently radiate said heat into space so that cracking or breaking due to overheating may not result. Preferably, though not necessarily, the plug 2 is of one piece. The socket or complementary member 7 which supports the plug may of course be of any suitable or ornamental design or pattern, and may assume a construction to which the term socket would no longer be applicable. Such chan es however would constitute no departure rom my invention. It may be stated in passing that the increased area of contact presented to the gases by the corrugations or roughenings r as against a deposit of the carbon than would a plane or blunt end.-

Having describedy my invention, what I claim is:

A spark-plug comprising an outer socket, an inner insulating lug mounted therein and terminating insidl the socket in a petticoat spaced from the. walls of the socket,

lthe inner walls of the petticoat being domed to form a pocket, a thread section tern1inatving the socket and provided with an axial passage-way discharging into the petticoat pocket, a `rbasin surrounding the discharge end of the passage-way, the edge of the inner wall of the basin forming the inner end of the passage-way aforesaid and disposed in a transverse plane slightly within the pocket of the petticoat whereby a short passage is formed between the free ends of the )etticoat and the inner walls of the basin or establishing communication between the passage-way of the thread section of the socket and the basin aforesaid, the basin communicating with the space between the socket and outer walls of the petticoat, an electrode extending axially through theV insulating lug and through the passage-way of the t read section of the socket and spaced from the walls of said passage-Way, and a coperating electrode carried by the socket.

In testimony whereof I affix my signature, in presence of two witnesses.

ARDEN J. MUMMERT. Witnesses: l

EMIL STAREK, Jos. A. MICHEL. 

